a) Field of the Invention
The present invention relates to a torsion predamping device comprising at least two coaxial parts, mounted rotationally in relation to one another within the limits of a determined angular clearance and associated with resilient predamping and centring means.
The present invention more particularly relates to an improvement to a predamping sub-assembly intended to dampen the impact of the shock between a hub and a hub disc at the end of their angular clearance.
b) Description of Related Art
In a known torsion damping device, one of the rotational parts bears a driven plate assembly intended to be rotationally connected with a first shaft, in practice a driving shaft, the crankshaft of the internal combustion engine in the case of an application to a motor vehicle, whereas another of the rotational part comprises a hub by which it is intended to be rotationally connected with a second shaft, in practice a driven shaft, the primary shaft of a gearbox in the case concerned of such a motor vehicle.
In such an assembly, from document FR-A-2 496 210 it is known for example to add a torsion predamping sub-assembly in which the delimitation of the angular clearance between the two coaxial parts is provided by loose meshing means provided with small studs, made of elastomer, placed on the loose meshing teeth of one of the coaxial parts, against which the loose meshing elements of the other coaxial part come to abut in order to reduce the noise of impact at the end of travel of the loose meshing means.
However this solution does have drawbacks. On account of their reduced size, the studs indeed only provide localised damping, resulting in a residual noise which can not be eliminated. Moreover, the service life of these elastomeric elements is limited and they weaken the teeth on which they are placed.